A precise speed signal is required among other things wherever electric motors are used for a drive whose regulation is supposed to occur more precisely than with a conventional block commutation. The speed signal can be determined via an angle signal which can be recorded with a commutation sensor. The angle signal and hence also the speed signal can however have interference which prevents a precise regulation of the electric motor. In the prior art there are solutions with which the interference is supposed to be corrected by a previously determined correction value.
DE 102 60 862 A1 shows a method for correcting an angle or distance measuring sensor arrangement in which sinus or cosine shaped measuring signals are evaluated, which are gained by scanning a moved measuring object. The correction of the angle or phase error of the measuring signals takes place by deriving constants from a plurality of measuring signals for estimation and correction of the angle and phase error and/or the amplitude of the measuring signals.
DE 101 33 524 A1 describes a method for correction of a dynamic error of a sensor. This dynamic error is superimposed on the sensor signal, for example in the form of periodic fluctuations whose frequency and amplitude change continuously with the speed of the motor. For correction of the dynamic error the sensor-output signal is fed to a filter circuit and a correction circuit. The correction circuit obtains one or more of the filtered signals emitted by the filter circuit and generates a corrected sensor signal from information that it obtains from a comparison of the filtered signals with the unfiltered sensor output signal.
DE 10 2011 105 502 A1 shows a method for adjusting a phase offset between a rotor location sensor and a rotor location of an electrically commutated motor. In so doing, the rotor location sensor measures a position of the rotor of the motor which is driven during operation with a block commutation. This measured position is compared to an expected position. A phase offset is formed from the difference between the measured and expected position, said phase offset being used for driving the electrically commutated motor. The position of the rotor is measured with an absolute value rotor location sensor which is set into relation with a motor parameter that characterizes the expected position of the rotor.